In recent years, a power semiconductor device (hereinafter referred to as a “transformer device”) including a transformer has been developed in the field of power electronics.
FIG. 5 is a schematic sectional view of a transformer device.
A transformer device 101 includes a first wiring layer 102 made of SiO2 (silicon oxide) on an unshown semiconductor substrate.
A first wiring trench 103 is formed in the first wiring layer 102. A first wire 105 made of a metallic material (hereinafter referred to as a “Cu wire material”) mainly composed of Cu (copper) is embedded in the first wiring trench 103 through a barrier metal 104. A coil groove 106, spiral in plan view, having the same depth as the first wiring trench 103 is formed in the first wiring layer 102 at an interval from the first wiring trench 103. A first coil 108 is embedded in the coil grove 106 through a barrier metal 107.
A diffusion preventing/etching stopper film 109 made of SiN and an interlayer dielectric film 110 made of SiO2 are stacked on the first wiring layer 102. Further, an etching stopper film 111 made of SiN and a second wiring layer 112 made of SiO2 are stacked on the interlayer dielectric film 110.
A second wiring trench 113 is formed in the second wiring layer 112. The second wiring trench 113 is dug down from the upper surface of the second wiring layer 112 to the upper surface of the interlayer dielectric film 110. A second wire 115 made of a Cu wire material is embedded in the second wiring trench 113 through a barrier metal 114. A coil groove 116, spiral in plan view, having the same depth as the second wiring trench. 113 is formed in the second wiring layer 112 at an interval from the second wiring trench 113. A second coil 118 constituting a transformer along with the first coil 108 is embedded in the coil groove 116 through a barrier metal 117.
The second wiring trench 113 is formed in a pattern having a portion intersecting with the first wire 105 in plan view. In the portion where the first wire 105 and the second wiring trench 113 (the second wire 115) intersect with each other in plan view, a via hole 119 passing through the diffusion preventing/etching stopper film 109 and the interlayer dielectric film 110 is formed between the first wire 105 and the second wiring trench 113. A via 121 is embedded in the via hole 119 through a barrier metal 120. Thus, the first wire 105 and the second wire 115 are electrically connected with each other through the via 121.
A diffusion preventing/etching stopper film 122 and an interlayer dielectric film 123 are stacked on the second wiring layer 112.